Concentration and use of methylcyclopentane in 2, 2, 4-trimethylpentane isomerization



July 21, 1953 F. E. coNDoN CONCENTRATION AND USE OF METHYLCYCLOPENTANE IN 2 2 4-TRIMETHYLPENTANE ISOMERIZATION Filed June 50, 1949 NOILVN OLLUVHJ tIOiVHVdEIS Hmm lllll INVENTOR.

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fom a IOZMDO 11 BOlDVI-IH lll NollvNolnvaJ 7" I. aoiovsa Patented July 2l, 1953 UNITED STATES PATENT OFFICE r CONCENTRATION AND USE OF METHYLCY- CLOPENTANEv IN 2,2,4-TRIMETHYLPEN- TANE ISOMERIZATION Francis E. Condon,-Bartles,villeOkla., assigner to Phillips Petroleum C of Delaware ompany, a corporation.

Application June 30, 1949,' Serial No. 102,394

3 Claims. (Cl. 260.--683-5) This invention relates to the isomerization of l 2,2,4-trimethylpentane, sometimes called isooctane, and the use Of methylcyclopentane therein as anl inhibitor of side reactions. In one of its. specilic aspects the invention pertains to the isolation, by chemical means, of methylcyclopentane from admixture with cyclohexane :and/or normal hexane, and use of the so-isolated material as an inhibitor in the aluminum bromidecatalyzed isomerization of 2,2,4-trimethylpentane to form' 2,3,4-trimethylpentane, 2,3,3-trimethylpentane, and 2,2,3-trimethylpentane.

In the preferred embodiments the invention relatesY to an integrated process wherein an isoparafnc by-product of the isomerization is emA ployed as reactant in the methylcyclopentane isolation step` Other preferred aspects of the invention involve the use ofthe methylcyclopentane isolation steps to segregate and remove cyclohexane formed in the isomerization step by a side reaction involving isomerization of the methylcyclopentane inhibitor used therein; p

This application is a ycontinuation-in-part of plicable as starting materials for chemical synl theses for which 2,2,4-trimethylpentane would be unsuitable. For example, 2,3,3-trimethy1pentane and 2,2,3-trimethylpentane can 'be lcatalytically hydrogeno'lyzed to triptane (2,3,3-trimethylbutane) and methane, whereas 2,2,4-trimethylpentane would not yield triptane on hydro-.- genolysis (Ind. Eng. Chem.,.39, 853 (1947)..)

The .isomerization of 2,2,4-trimethylpentane with aluminum bromide at 26 C., for example, results in an approximately 26` Weight percent ultimate. yield of isomers, of which aboutA 85 per cent are the trimethylpentanes other than 2,2,4- trimethylpentane. If the isomerization is conducted in the presence of methylcyclopentane, however, the ultimate yield of isomers is `in creased to as much as 65 per cent or more `of th 2,2,4-trimethylpentane converted.

Methylcyclopentane, however, is ordinarily obtained .irl admixture with normal hexane and yclohexane. Both of'4 these. hydrocarbons are ineiective in increasing the yield of isomers from then 2,2,4-trimethylpentane and undergo practically no change during the isomerization of the 2,2,4-trimethylpentane. monly obtained mixture of methylcyclopentane,

normal hexane and `cyclohexa'ne Were used in ad-` mixture With 2,2,4-.trimethylpentane duringisomerization of the latter in order to obtain the benecial effects of the methylcyclopentane on the yield of isomers fromthe 2,2,4-trimethylpentane, the inert cyclohexane and normal hexane would accumulate in recycle streams containing valuable methylcyclopentane, which would eventualli7 have to be Withdrawn and discarded, at least in part. Y Furthermore, the presence of the nerts, cyclohexanefand normal hexane,`would lnecessitate the use 0l?l enlarged equipment for the treatment of a given amount of 2,2,4-trimethylpentane in a given time. Consequently, it is advantageous to concentrate. the methylcyclopentane from` its admixture with cyclohexane and normal hexane in order to use it most effectively as an inhibitor of side reactions during the isomeriz-ation of 2,2,4-trimethylpentane. f

Methylcyclopentane (B. v P. 71.8 C.) 4can be separated from normal hexane (B. P. 68.7 C.) y

and from cyclohexane (B. P. 80.7 C.) by fractional distillation. But the closeness of the boiling points of these three hydrocarbons requires that the fractionating equipment be rather complex and .exceedingly elcient. A Methylcyclopentane can be separated from cyclohexane and no1'- mal hexane, however, by a chemical means requiring inelaborate fractionating equipment, as described in my copending application, now U. S. Patent No. 2,474,827. As disclosed therein, a mixture of methylcyclopentane with cyclohexane and/or normal hexane maybe contacted with tertiary-butyl chloride, or othertertiary or less preferably secondary alkyl or cycloalkyl halide,

in the presence. of aluminum chloride or bromide so as to eiect as the' principal reaction a halogen- Y hydrogen exchange whereby the methylcyclopentane is vconverted to a tertiary halide, 1-ch1oro1 methyl-cyclopentane, and the tertiary-butyl chlo- .ride is converted to isobutane:

` CH3 CH3- tional distillation from vthe other .components inl Thus, if such acome the mixture. It is then contacted in a second stage with sobutane or isopentane in the presence of aluminum chloride or bromide so as to effect as the principal reaction a halogen-hydrogen exchange whereby the l-chloro-l-methylcyclopentane is reconverted to methylcyclopentane andthe isobutane is converted to t-butyl chloride.

CH3 CH3 At least part of the isobutane used as reactant in this stage may be thatfor-med in the` first stage above. But in accordance with a preferred embodiment of the present invention, a part of this isobutane, that used to replace losses en-` gendered by the ineiciency of the chemical reaction for example, is obtained as a by-product of the 2,2,4-trimethylpentane isomerization stage as dis-closedfurther herein. Y

Methylcyclopentane, then, is obtained by fractional distillation from the product'of the second halogen-hydrogen exchange step just described and in accordance With the copending application, now U. S. Patent No. 2,474,827. In the practice of the present invention, this methylcyclopentane, freed from cyclohexane and vnormal hexane, `is admixed with 2,2,4-trimethylpentane and the mixture is contacted'with an aluminum halide isomerization catalyst in'ordcr to isomerize a part of the 2,2,4-trimethylpentane. 'Now it is a characteristic of thislisomerization reaction that isobutane is produced as a by-product in an amount corresponding to'about 18-25 per cent of the 2,2,4-trimethylpentane converted. Furthermore, although methylcyclopentane inhibits the formation of most of the by-products formed during isomerizration of the 2,2,4-trimethylpentane, it does not inhibit the formation of the isobutane. Therefore, isobutane is made available by the isomerization step and, according to the practice of the present invention, is utilized at least in part in the second halogen-hydrogen exchange step described above in which l-chlorol-methylcyclopentane is converted to methylcyclopentane.

During the isomerization of 2,2,4-trimethylpentane in the presence of metliyicyclopentane,

a part of the methylcyclopentane is isomerized to cyclohexane, which would tend to accumulate in recycle streams unless a part of it were continually removed. As an additional feature of this invention, therefore, a part of the methylcyclopentane recycle stream is diverted to the first' halogen-hydrogen exchange stage, the cyclohexane is removed and discarded Whilethe methylcyclopentane is recovered for reuse in the isomerization step. A n A From the foregoing it will be apparent that a principal object of this invention is to vprovide a process for the isomerization of 2,2,4-trimethylpentane wherein use of methylcyclopentane Vas an inhibitor of side reactions is facilitated by removal of cyclohexane and/or normal hexane found in admixture therewith in the primary source of the methylcyclopentane and/or formed by a concurrent isomerization of part of the methylcyclopentane being used as inhibitor.

Another object of the invention is to isolate methylcyclopentane from admixture with cyclohexane and/or normal hexane for use as an inhibitor of side reactions in the isomerization of 2,2,4-trimethylpentane, thereby increasing the yield ofA desired `trimethylpentaneV isomers.

A further object is to get rid of cyclohexane formed in the methylcyclopentane-inhibited isomeriz'ationA of 2,2,4-trimethylpentane.

Yet another object is to employ a halogenhydrogen exchange reaction for separation of methylcyclopentane from cyclohexane found in admixture therewith both in a primary source of same and in a recycle stream in a 2,2,-trimethylpentane isomerization process.

A still further object is to utilize light isoparafiinic material formed as by-product by the isomerization of 2,2,4-trimethylpentane as reactant for converting 1-chloro-l-methylcyclopentane into methylcyclopentane which is employed as inhibitor in Vsaid isonierization.

Further objects and advantages of my invention will be apparent, to one skilled in the art, from the foregoing and following disclosure and discussion.

The accompanying drawing shows schematically one arrangement of apparatus elements and now of materials theretl'irough suitable for the practice of my invention in a preferred embodiment. It will be understood that the drawing is diagrammaticV only, and that many suitable conventional forms of equipment may be employed as desired for any particular situation. Auxiliary elementsof apparatus, such as pumps, valves, heat exchangers, agitators, coolers, condensers, separators, automatic control means, and the like, are not shown in the drawing for the sake of simplicity, inasmuch as the supplying of such elements is Well within the'skill of the art.

In the drawing a commonly available mixture of methylcyclopentane, cyclohexane and normal hexane, such as one derived by simple fractional distillation of natural gasoline, enters reactor l through inlet conduit 2. Tertiary butyl chloride enters reactor l lthrough conduit 3. Suitable halogen-hydrogen exchange catalyst, such as a fluid aluminum chloride-hydrocarbon complex, enters reactor A. through line 5. Reactor 4 may comprise any suitable equipment for effecting a rapid and intimate intermixture of reactants with catalyst, -for example a mixing pump or agitated pressure vessel. The rate of flow of reaction mixturethrough reactor 4 is chosen to give the desired short reaction time. Contents of reactor are withdrawn through line 6 into settler 'l in which a heavier catalyst phase separates from a lighter hydrocarbon phase. If necessary or desired, Water or other materials for quenching the reaction may be introduced through conduit 3D. The heavier catalyst phase is Withdrawn from lsettler 'l' through outlet line 8 and may be revivifled by means not shown, for example by addition of fresh solid aluminum chloride. Preferably at least part of the catalyst phase is recycled from settler l via lines 8, 9 and 5 to reactor The catalyst-free lighter hydrocarbon phase is passed from settler l through conduit I to fractionation system H Which ordinarily comprises a series of two or more fractional distillation columns and associated equipment. Prior to fractionation this phase maybe treated by conventional means to remove dissolved :and/or suspended catalyst.

From fractionator Il, the following fractions are Withdrawn: (l) A Vlow-boiling fraction, comprising chiefly isob-utane, which is passed through line I2 to reactor I8. (2) A fraction, comprising unreacted tertiary-butyl chloride, which is recycled, as through lines i3, l5, 3 and 2 to reactor 4. (3) A fraction, comp-rising a cyclohexanen-hexane concentrate containing some methylcyclopentane, which may be Withdrawn as a product .of the process throng-lr outlet 114, but' part. of which is preferably recycled; as through conduits I4, I5, and 2 toJ reactor 4:fory further `concentration. Thel concentraterecovered through line I4 maybe passed to. a separate. isomerizaton stage (not shown in thedrawng), in which afpart ofthe cyclohexane is converted to methylcyclopentane and a part" ofthe. normalhexaneiis converted to isoliexane, and from whichl a. cyclohexane-nshexane fraction, enriched in methylcyclopentane, isy returned towreactor-'Il through line 2. (4) A fraction, comprising 1chloro1 methylcyclopentane, which is passing through lines I5 and I2 to reactor I8; (5i): A minor frac tion, comprising heavy hydrocarbons formed 'by side reactions such as alkylation and/orpol'ymer'- ization, which is.:withdrawn through outlet I1.

The mixture of isobutane and l-chloro-lmethylcyclopentane in line I2, supplemented from line 32 as needed with isobutane formedA in reactor in order to maintain preferably at least a 1:1 mol ratio of' isobutane to 1chloro-1- methylcyclopentane, is passed to reactor I8, in which it is intimately contacted with fluid aluminum chloride-hydrocarboncomplex catalyst or other suitable catalyst, which is introduced through lines 5 and I9. After allowingthe desired reaction time, the effluent from reactor I8 y is passedv through conduit 20 to settler 2-I in which a heavier or catalyst phase separates from a lighter or hydrocarbon-rich. phase. The heavier phase may be withdrawn through outlet 22 forrevivication, but is preferably recycled at least in part through lines 23 and I9l to reactor I8. If necessary or desired, water or other materials for quenchingv the reaction may be introduced through line 3|.` The lighter hydrocarbon phase from settler 2I may be treated for removal of dissolved and/or suspended catalyst by means not shown. This phase is passed through line 24 to fractionator 25 which, in practice, is usually a series of fractionating columns. From fraction system 42.

tionator 25, the followingy fractions are Withdrawn: (1) A low-boiling fraction, comprising whichV is withdrawn from the system through i outlet 29.

The methylcyclopentane in line. 21 is admixed with 2,2,4-trimethylpentane from line 33 and this mixtuer is contacted in reactor 35 with an aluminum halide isomerization catalyst from line 34, preferably aluminum bromide. A catalyst activator, such. as the corresponding hydrogen halide, may also be used in reactor 35 if desired. From reactor 35 the reaction mixture passes through line 36 to separator 38,L from which the catalyst is removed through line 3,9, for example as a water solution resulting from the addition of Water as a quench from line 31. If practicable, a portion of the catalyst may be recycled to reactor 35 through lines 4D and 34. A hydrocarbon phase is passed from separator 38.v through line '4i to fractionation meansv 42 which'v inpractice is a series of fractionatingv` columns. If further arator 38 is required `for removal oftentrained or dissolved; catalyst', such treatment may be applied prior to entry of this phase into fractiona- From fractionator 42 the following fractions are withdrawn: 1) A low-boiling fraction, comprising mainly isobutane, with or4 without usually smaller quantities of isopentane, both formed in reactor 35, which is withdrawn through line 43 and at least a part of which is passed through lines 32 and I2 toreactor. i8 vWhere-it isusedin a halogen-hydrogen exchange reaction with 1chlorolmethylcyclo pentane to produce methylcyclopentane. (2)'` A fraction comprising mainly unreacted methylcyclopentane but also containing a minor portion of cyclohexane, formed in reactor 35 by isomerization of methylcyclopentane therein, which is withdrawn through line 44 and is recycled in part through lines 45 and 21 to reactor 35, and a part of which is returned through lines 44'and I5fto reactor 4 for the eventual removal of the cyclohexane. (3') A fraction comprisingv mainly unreacted 2,2,4-trimethylpentane, which is withdrawn through linel 46 and is recycled through lines 45 and Zrto'reactor 35'. l(4) A fraction, comprising mainly octanes otherthan 2,2,4-trimethylpentanm which is withdrawn through line 4l as a product of theprocess. (5) A fraction comprising higher-boiling hydrocarbons which is withdrawn through line 48.

The preferred temperature .rangeforthe rst halogen-hydrogen exchange reaction, carried out in reactor 4, is 0 to 40 C., although much lower temperatures may also. be used. Elevated pressures suiiicient to maintain the reaction mixture in liquid phase are preferred. The reaction time should be short and is usually within the range of 0.05 to l0 minutes; a reaction time of one minute is ordinarily preferred, inasmuch as long reaction times favor undesired side reactions with consequent reduction in ultimate yield. Although the proportion of the tertiary or secondary alkyl halide added is not critical, it is preferredthat the mol ratio of added alkyl halide to methylcyclopentane be at least about 1: 1, and preferably somewhat in excess thereof. Aluminum bromide as well as aluminum chloride is a highly satisfactory catalyst. Other active metal halides of the Friedel-Crafts type may likewise be used. The catalyst may be employed in any conventional form, but preferably a hydrocarbon-aluminum halide complex is employed which takes the Vform of a heavy liquid containing from 40 to 60 or '70 weight per cent aluminum halide. Although the halogen of the catalyst need not necessarily cor-- respond to the halogen of the added tertiary or secondary alkyl halide, it is preferred that they so correspond in order to facilitate recovery or reuse of materials Without having to contend with exchange of halogen between catalyst and reactants. Relatively small amounts of catalyst are required, preferably ranging from 1 to 5 Weightpercent of the reaction mixture, although smaller amounts such as 0.5 per cent or lower, ory larger amounts up to 10 or even 25 per cent, or more, are operable.

Reaction conditions of temperature, pressure, time, and catalyst for the second halogen-hydrogen exchange reaction, carried out in reactor I8, may be similar to those described above for reactor 4 although. it is preferred. that the mol; ratio of added tertiary hydrocarbon (isobutane and/or isopentane).A to the tertiary halide 1-chloro-1- methylcyclopentane which is to be reconverted intofthe original:methylcyclopentane be atleast about 1:1, and preferably somewhat in excess thereof.

Although tertiary butyl chloride is the preferred reactant for the ifirst halogen-hydrogen exchange reaction, various other tertiary, or less preferably secondary, alkyl and cycloalkyl halides, preferably the chlorides and bromides, may

Y be employed so long as the boiling point relationships described hereinabove are such as to allow 4recovery of the desired intermediate 1-chloro-1- methylcyclopentane by simple fractional distillation. Thus, isopropyl chloride, sec-butyl bromide, 2-chloro-2-methylbutane(tert-amyl chloride), and other halides containing not in excess of seven carbon atoms per molecule, may be used.

The following data are given to illustrate specie conditions suitable for practicing the halogen-hydrogen exchange reaction steps of the invention. 1t will be appreciated, of course, that the exact conditions stated are merely exemplary and are not limiting as to the broader aspects of the invention.

A mixture of 114.7 grams of t-butyl chloride (1.24 moles), 114.3 grams of methylcyclopentane (1.36 moles) and 38.5 grams of cyclohexane, cooled in ice, was stirred vigorously with 4.0 grams of A1013 for 120 seconds. Then 25 cc. of water was `added to wash out the A1Cl3. When the dried hydrocarbon mixture was fractionated, there were obtained 18d-grams (0.31 mole) of isobutane, 76.2 grams (0.83 mole) of unreacted t-butyl chloride, 84.9 grams (1.01 moles) of unreacted methylcylopentane, 32.2 grams f cyclohexane, 36.0 grams (0.30 mole) of l-chloro-lmethylcyclopentane and 4.1 grams of high-boiling residue.

A mixture of 150.2 grams (1.2'7 moles) of 1- chloro-l-methylcyclopentane prepared in several runs from a mixture of methylcylopentane and (1.2 moles). 36.5 grams of t-butyl chloride (0.40 mole), 41 grams of the regenerated methylcyclopentane (0.49 mole), 80 grams (0.68 mole) of unreacted 1 chloro-l-methylcyclopentane, and some high-boiling residue.

Suitable conditions for the isomerization. of 2,2,4-trimethylpentane, in addition to requiring the presence of methylcyclopentane as inhibitor, involve the use of moderate temperatures and reaction times. The reaction is best conducted in the liquid phase. Temperatures of from -30 to C. are suitable, with the range of -10 to +30 C. being preferred. Other factors being equal, decreased temperatures give increased ultimate yields, though the reaction rate is slowed. Contact times of from 1 to 500 minutes are generally satisfactory, with two hours or less, or preferably one hour or less, usually employed.l The quantity of catalyst may be varied considerably without greatly affecting the ultimate yield of octanes, at least within the range of 2 to 15 weight per cent aluminum chloride based on the weight of 2,2,4-trimethylpentane charged. Even small quantities of methylcyclopentane are helpful; I prefer to employ a mixture of 2,2,4-trimethylpentane and methylcyclopentane containing at least 10 weight per cent of the latter, and up to 25 or even 50 per cent may be used. Suitable catalyst activators and various other isomerization procedures known to the art may be used as desired.

The data presented in Table I are examples of results obtainable in the isomerization of 2,2,4-trimethylpentane with aluminum bromide catalyst. The runs were carried out at 26 C. in a 500 ml. glass flask; at the end of the specied reaction time the aluminum bromide was washed out with water. Obviously these runs are only exemplary, and not necessarily representative cyclohexane as descr1bed above, and 107 grams 40 of the optimum conditions for all cases.

TABLE I Aluminum bromide zsomerzzatzon of 2,2,4-Trimethylpentanea Run No 1 l 2 3 4 5 7 AlBrn, Wt. Percent of Octane e 5. 9-13. 3 0. 8 9.7 9. 5 10 7 9. 3 9.4 Contact Time, Min 40-240 130 60 45 45 180 10 Charge Compri., Wt. Percent: v

2,2,4-trimethylpentane 100 88. 8 S7. 5 85. 5 77. 8 76. 7 74. 8 Methylcyclopentane 0 12. 5 14. 5 22. 2 0 25. 2 Cycloliexane 0 11. 2 0 0 0 23. 3 0 Product Compu., Wt. Percent:

Isobutane 1.93 6 16 4.21 5.51 1.57 2.06 Isopentane 0.55 0 12 0.08 0.05 0.48 0,01 Hexanes and Heptanes d 0.27 Methylcyclopentane 13. 2 5. 3 6. 8 l1. 8 e 24. 7 21. 7 Cyclohexane 1. 05 2,2.4-trimethylpentane 77. 2 62. 9 67. 9 53. 3 67. 3 62. 4 Other Octanes. 3.0 11.5 10. 9 14.2 2.4 8. 0 Nonanes and Heavier 3. 4 13. 7 9. 7 13. 5 2, 0 5.7 Catalyst Sludge Oil 0.67 0.3 0.4 0.3 0.65 0.15 Conversion, Wt. Percent:

2,2.4-trimethylpentanc 1l. 8-35. 1 13. 1 28. 1 20. 6 32. 2 12. 2 17. 0 A lBrg to Sludge 20-78 33 l0 10 7 28 5 Ultimate Yield, Wt. Percent Octane Conv.:

Isobutane 1S. 35:0. 6 16. G 25. 0 23. 9 22.0 1G. 7 16. 7 Isopentane 6.0:1:0.5 4. 9 0.5 0.5 0.2 5.1 0.1 1(hlctancs. d t zh 25. 8 46.8 61.8 56.6 25. 4 62.9

exzmes an Vep ane :l: .8 09+ and Sludge OL SSALS 52.7 27.7 13.8 21.2 52 8 20.3

e The temperature was 26 C. in all the runs.

d By difference.

No methylcyclopentane.

(1.84 moles) of isobutane, was stirred with about 6 grams of AlCla at 0 C. for about '7 minutes. Water was added, the material then dried, and the dried reaction mixture was fractionated.

Run 1 is an average of the data of 10 runs on the isomerization of 2,2,4-trimethylpentane alone. Runs 3, 4, 5 and 7 illustrate the benecial effect of methylcyclopentane on the ultimate There were obtained about grams of isobutane 75 yield of octanes from the 2,2,4-trimethylpentane.

amants A comparison 'of ru'S with-run 41a`11d'ofjrung5 withrun 7 shows that, in thefpresence of methylcyclopentane, better ultimate yields of octanes are obtainable at the lower conversions. A considerable portion of. the methylcyclopentane is consumed, possibly by alkylation or other reactions. AIt is preferable to recycle methylcyclokshows that'somecyclohexane is formed by isomerization of methylcyclopentane during the isomerization of the 2,2,4-trimethylpentane; and therefore provision must be made for the continuous removal. of .thel cyclohexanewhich would otherwise build-up in the reaction mixture. Such provision is described hereinabove. Runs .z gandz show that cyclohexane has no beneficial reifect on the ultimate yieldl of octanes from` the 2,2,4- trimethylpentane; and the total weight per cent f Cs plus Cv in each of these runs indicate that the cyclohexane is unchanged. A much larger quantity of the AlBrs .goes to sludge with cyclohexane added than with methylcyclopentane added. It appears that, in order to inhibit side reactions during 2,2,4-trimethylpentane isomerization, a naphthene must havel a reactive tertiary hydrogen, as in methylcyclopentane. Since normal hexane, like cyclohexane, has no reactive tertiary hydrogen, it would be expected to be inert during 2,2,4-trimethylpentane isomerization with aluminum bromide at the low temperatures specified here. It lacks the vbenecial inhibiting effects of methylcyclopentane and is an undesired diluent since itis not isomerized itself under these conditions.

I claim:

1. A process which comprises subjecting a hydrocarbon mixture partially derived from an extraneous source and partially derived from a recycle stream hereinafter described, said mixture comprising methylcyclopentane and cyclohexane, to reaction with a halide selected from the group consisting of secondary and tertiary alkyl and cycloalkyl halides under conditions effecting halogen-hydrogen exchange reaction to form l-halo-l-methylcyclopentane, separating from the reaction mixture by fractional distillation l-halo-1-methylcyclopentane so produced, reacting same with a low-boiling saturated hydrocarbon having a tertiary carbon atom and at least partially derived as hereinafter described under conditions effecting halogen-hydrogen exchange reaction re-forming methylcyclopentane, subjecting 2,2,4-trimethylpentane in admixture with thus-formed methylcyclopentane to isomerization in the presence of an aluminum halide isomerization catalyst selected from the group consisting of aluminum chloride and aluminum bromide under conditions forming isomeric octanes and low-boiling saturated paraffin hydrocarbon having a tertiary carbon atom, said methylcyclopentane inhibiting side reactions during said isomerization, recovering isomeric octanes so produced as a product of the process, passing at least a portion of said low-boiling saturated parafn hydrocarbon having a tertiary carbon atom to halogen-hydrogen exchange reaction with said l-halo-l-methylcyclopentane as hereinbefore described, recovering from effluents ofA said isomerization a fraction comprising unreacted methylcyclopentane containing in admixture therewith cyclohexane formed by isomerization of methylcyclopentane, recycling a portion of said fraction to said isomerization,

1U and'fpassing a portion of :said fraction. asV part `of said 'hydrocarbon 'mixture-to halogen-hydrogen exchange areac'tion rwith fsad. :halide to separate from/cyclohexane nthefL:methylcyclopentane'con-v tent thereof as'hereinbefore 'des'.cribed.

f.' A :'process- {which} `comprisessi. subi eating a hydracarbon miixturespartially rlr-zrived:from :an extraneousonrce @andi partially-derive@ from 'a recycle -zstream ihereinafterdescribedarsaid j rmix.- ture :comprising #methylcyclopentane .and cyclohexane, l to reaction'with"af'halide selected `from the. group; consisting-y of secondary and vtertiary alkyl and', cycloalkylnhalidesz fin; the v presence vof, a tliriedeleG-rafts ype':metal:.'halidev catalyst* under V-dmnditions` eiectingf :halogen-hydrogen .-:zexchange; `:reaction .atoz Fform .l-halo-l .lr-:methylcyclopentanejfzsaid lconditions vvcomprising temperaturesznotexceedingelfC. and: reaction timemot -a tertiary carbon atom and at least partially derived as hereinafter described in the presence of a Friedel-Crafts type metal halide catalyst under conditions 1 effecting halogen-hydrogen exchange reaction re-forming methylcyclopentane, said conditions comprising temperatures not exceeding 40 C. and reaction time not exceeding 1G minutes, subjecting 2,2,4-trimethylpentane in admixture with thus formed methylcyclopentane to isomerization in the presence of van aluminum halide isomerization catalyst selected from the group consisting of aluminum chloride and aluminum bromide under conditions comprising temperatures within the range of -30 to +50 C. and reaction time not exceeding two hours forming isomeric octanes and low-boiling saturated paraiin hydrocarbon having a tertiary carbon atom, said methylcyclopentane inhibiting side reactions during said isomerization recovering isomeric octanes so produced as a product of the process, passing at least a portion of said low-boiling saturated paranin hydrocarbon having a tertiary carbon atom to halogen-hydrogen exchange reaction with said l-halo-l-methylcyclopentane as hereinbefore described, recovering from eilluents of 'said isomerization a fraction comprising unreacted methylcyclopentane containing in admixture therewith cyclohexane formed by isomerization of methylcyclopentane, recycling a portion of said fraction to said isomerization, and passing a portion of said fraction as part of said hydrocarbon mixture toV halogen-hydrogen exchange reaction with said halide to separate from cyclohexane the methyl-- cyclopentane content thereof as hereinbefore described. v

3. A process which comprises subjecting a hydrocarbon mixture partially derived from an extraneous source and partially derived from a recycle stream hereinafter described, said mixture comprising methylcyclopentane, cyclohexane and normal hexane, to reaction with a tertiary Y Ilv jecting 2,2,4-trimethylpentane in admixture with thus-formed methylcyelopentane to isomerization in the presence of an aluminum Vbromide isomerization catalyst under conditions forming isomeric octanes and isobutane, said methylcyclopentane inhibiting side reactions during said isomerization, recovering isomeric octanes so produced as a product'of the process, passing at least a portion of said isobutane to halogen-hydrogen exchange reaction with said l-halo-l-methylcyclopentane as hereinbefore described, recovering from effluents of said isomerization a fraction comprising unreacted methylcyclopentane containing in admixture therewith cyclohexane formed by isomerization of methylcyclopentane, recycling a portion of said fraction to said isomerization, and passing a portion of said fraction as part of said hydrocarbon mixture to 12 halogen-hydrogen exchange reaction 'with said tertiary alkyl halide to 'separate from cyclohexane the methylcyclopentane content thereof as hereinbefore described.

FRANCIS E. CONDON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,394,797 McAllister et al. Feb. 12, 1946 2,440,751 Legatski May 4, 1948 2,468,746 Greensfelder et al. ,May 3, 1949 2,474,827 Condon July 5, 1949 OTHER REFERENCES Ipatiei et al.: Ind. Eng. Chem., vol. 28, pp. 

1. A PROCESS WHICH COMPRISES SUBJECTING A HYDROCARBON MIXTURE PARTIALLY DERIVED FROM AN EXTRANEOUS SOURCE AND PARTIALLY DERIVED FROM A RECYCLE STREAM HEREINAFTER DESCRIBED, SAID MIXTURE COMPRISING METHYLCYCLOPENTANE AND CYCLOHEXANE, TO REACTION WITH A HALIDE SELECTED FROM THE GROUP CONSISTING OF SECONDARY AND TERTIARY ALKYL AND CYCLOALKYL HALIDES UNDER CONDITIONS EFFECTING HALOGEN-HYDROGEN EXCHANGE REACTION TO FORM 1-HALO-1-METHYLCYCLOPENTANE, SEPARATING FROM THE REACTION MIXTURE BY FRACTIONAL DISTILLATION 1-HALO-1-METHYLCYCLOPENTANE SO PRODUCED, REACTING SAME WITH A LOW-BOILING SATURATED HYDROCARBON HAVING A TERTIARY CARBON ATOM AND AT LEAST PARTIALLY DERIVED AS HEREINAFTER DESCRIBED UNDER CONDITIONS EFFECTING HALOGEN-HYDROGEN EXCHANGE REACTION RE-FORMING METHYLOCYCLOPENTANE, SUBJECTING 2,2,4-TRIMETHYLPENTANE IN ADMIXTURE WITH THUS-FORMED METHYLCYCLOPENTANE TO ISOMERIZATION IN THE PRESENCE OF AN ALUMINUM HALIDE ISOMERIZATION CATALYST SELECTED FROM THE GROUP CONSISTING OF ALUMINUM CHLORIDE AND ALUMINUM BROMIDE UNDER CONDITIONS FORMING ISOMERIC OCTANES AND LOW-BOILING SATURATED PARAFFIN HYDROCARBON HAVING A TERTIARY CARBON ATOM, SAID 